Just because you're at work doesn't mean you can't take a break now and then. And there are solid reasons to goof off, too.
In particular, "leisure browsing" at work is a good thing, according to a 2009 study by the University of Melbourne. It found that people who spend up to 20 percent of their time at work surfing the Internet for fun are more productive by about 9 percent than people who don't. (No word on whether the dawdlers in the Australian study also put in up to 20 percent longer workdays, but it wouldn't surprise us.)
The boss may disagree, however, so remember to cite this study if you get caught doing personal stuff on company time. Then again, if you take the tips in this slideshow to heart, you may never be caught.